Backlighting helps to improve the readability and the color gamut of a display, such as an LCD display. The amount of improvement is at least partially based on the emitted intensity profile of the backlighting so designers look for ways to improve this intensity.
One prior solution has been to place a film containing prisms on the output side of a backlight. This film effectively increases the on-axis brightness of the backlight, at the expense of the lower-valued light that is emitted obliquely and a harsh transition between them. Unfortunately, the emission profile from a prism film is not ideal for all types of displays. For example, the ideal emission characteristics of an LCD television are somewhat broader and having a softer intensity roll-off than that for an LCD display for a laptop computer.